In the Garden:New England
September, 2008
Regional Report

Vases hold an array of flower colors and shapes, but these dahlias are at their best standing tall in the garden.

Saving Dahlias

I went all out on dahlias this year. I usually plant a few every year, and if I like the flowers, I dig up the tubers and store them over the winter. In the past, if they didn't survive winter storage, it wasn't the end of the world. But this year I have the cream of the crop of dahlias and it WILL be the end of the world if they don't make it through the winter. I wanted tall dahlias with good, strong stems and flowers with personality. I ordered six different varieties -- different colors and flower types -- from a nursery that specializes in dahlias, and I got my money's worth. The plants are sturdy and the flowers are gorgeous.

Now, with frost a possibility any time now, I'm planning how and where to organize their winter sleeping quarters so I can enjoy them in years to come. This process begins when the first hard frost kills the foliage.

Digging
Because dahlias are not hardy in New England, we need to dig up the tubers before winter and store them indoors in a cool location, or in a garage that doesn't get below freezing. After a hard frost kills the foliage, cut off the top growth, leaving about 6 inches of stem attached to the clump of tubers. You can leave the tubers in the ground for up to a week (as long as the ground doesn't freeze) to give their eyes (buds) more time to develop. Or you can dig them right away. Use a spade or a shovel to get as much of the clump as possible. And be sure to attach a label with the variety name.

Drying
Once dug, the tubers need to dry a bit so they will store well. Gently shake off excess soil and either rinse the tubers now, then let them dry; or don't rinse them before drying. Either way, letting them dry and cure for several days in a cool location is essential. A garden shed or a root cellar or a garage will work. Keep the label with the clump.

The tubers I bought had the names imprinted right on the tubers so it was easy to tell them apart before planting. Very handy. I'd like to try this method using an indelible pencil, but as insurance against losing track of what's what, I'm going to keep each variety in its own box. I'm also going to take a picture of each variety while it's still in bloom, write the variety name on the photo, and attach the photo to the box that will store that variety.

Storing
Once tubers are dry, separate each one from the clump, keeping a portion of the stem attached. Make sure each tuber has at least one eye at the base of the stem. I'm going to store each variety in its own labeled cardboard box -- playing it safe in case the marking pen doesn't work. Opinions abound on the best storage medium (peat moss, vermiculite, sawdust, etc.) and whether to enclose them in plastic bags or not. It depends on whether your location is very dry or somewhat humid. I'm going to slip the tubers into plastic produce bags (with some holes punched into them) containing vermiculite, and set the bags in the boxes lined with newspaper.

Note: If you have a dehumidifier in the storage room, better protect the tubers in plastic bags. You might even need to slightly moisten the vermiculite to keep the tubers from desiccating during storage.

Spot-check some tubers during the winter and remove any that are rotting. If they look shriveled, slightly moisten the vermiculite or spray the newspaper with water.